California Rep. Ronald V. Dellums announced his candidacy for the Democratic presidential nomination today, saying he was running in order to force debate of issues important to blacks, Hispancis and the poor.

"The tragic reality of this convention is that we are not in the forefront of the struggle," Dellums told black convention delegates and Democratic party workers. "This convention has been watered-down pablum."

Describing President Carter's control of the convention as well-oiled body in front of a moving train.

In order for his name to be placed in nomination on Wednesday night. Dellums would have to get a petition signed by 333 of the 3,331 convention delegates. If nominated, he would then get an opportunity to address the convention -- possibly in prime time.

There appeared little possibility that Dellums would get more than a handful of votes even if his name was placed in nomination. There was 481 black delegates here -- two thirds of them pledged to Carter and the rest to Sen. Edward M. Kennedy. This did not seem to matter to the maverick congressman from the San Francisco Bay area.

"Yes, my candidacy is a last-ditch effort. It is a desperate attempt to say there needs to be some integrity to the process, that the issues of this country need to be discussed and debated," Dellums said.

He decried the absence here of any discussion of the resurgence of the Ku Klux Klan or of the problems that led to riots this summer to Miami and Chattanooga.

"What has happened in 25 years that we are no longer prepared to struggle for the poor, the downtrodden?" he asked.

Dellums said he hoped his announcement would lead to the emergence of other issue-oriented favorite son candidates for the presidential nomination, "if for no other reason than to stop this train."

This afternoon, blacks from 13 states threatened to walk out of the convention, but the potential rebellion was put down when 15 of the blacks met with Carter campaign officials Robert S. Strauss and Hamilton Jordon, who promised they would meet Tuesday with all of the black delegates and alternates to the convention.

The blacks said they were pushing the Carter aides for improved access to the White House, more vigorous federal action against police brutality and efforts to reduce unemployment among youths.